He was born on Biel-tan and was a master of the combat form Imuluan. He fought against Hive Fleet Leviathan where his sister, Eminielle, was killed: her spirit stone was later forged into his weapon. He was captured by the Eldar pirate lord Hiriaq and was spared by Hiriaq after his retinue slew many of Hiriaq's men. He was then inducted into the pirate's bodyguard.
When Hiriaq was killed by a traitor, Alanthrasil tasked the pirate fleet on raids against Imperial shipping. The Inquisition devised a scenario where they would draw the pirates into battle with an ork fleet, which resulted in the destruction of much of Alanthrasil's fleet but he was saved by Inquisitor Lichenstein and Battlegroup Gravis, insisting that Alanthrasil serve him for a year as recompense.